We have defined and compared some of the functions in vitro of polymorphonuclear neutrophils collected from either peripheral blood (PB-PMN) or gingival exudate (CR-PMN) in healthy human subjects. We have shown that CR-PMN have a diminished capacity to further phagocytose opsonized particles in vitro as compared to PB-PMN and that a smaller proportion of CR-PMN bear Fc receptors for IgG than PB-PMN. We have demonstrated that there are more activated PMN in the gingival exudate than in the blood but that those activated CR-PMN apparently produce less superoxide anion per cell that the PB-PMN. We have also observed that CR-PMN have a diminished capacity to migrate in vitro. These different functions have been studied to define baseline data for further studies of the same functions of PMN from patients with diseased periodontium. In addition, we have developed a novel, sensitive quantitative assay for oxygen intermediates.